"Credit the campaign's organization in the caucus states -- Obama won supermajorites in Alaska (75%), Kansas (74%), Colorado (68%), Minnesota (68%) and in the primary state of Georgia (68%). Obama's margin of victory in Illinois was proportionately larger than Clinton's margin in New York -- more than enough to give him some extra delegates."

http://marcambinder.theatlantic.com/arch ives/2008/02/why_did_obama_win_more_dele gat.php